The invention relates generally to the construction of a forced flow fluid heating unit, and more particularly to improvements in the construction and arrangement of fluid heating circuits especially adapted for use as a furnace wall support.
The present invention is directed at improvements in the construction of forced circulation once-through vapor generators of the type disclosed in U.S. Pat. Nos. 3,665,893 and 3,834,358 wherein the upright boundary walls of the furnace are subdivided into upper and lower portions and include at least one separate continuous upflow fluid heating pass in each of the wall portions with tube segments of the separate fluid heating passes forming a common plane wherein they are interlaced and coextensive, while above and below this common plane, the tubes are bent outwardly of the plane of the wall and connected to suitably arranged headers which allow for equalization of enthalpies as the fluid flows from one heating pass to the other.
The construction of walls of the character described is costly and time consuming in that it requires the individual bending of relatively short tube lengths and the manual welding of each of these tube lengths above and below the common plane formed by the interlaced tube segments of the fluid heating passes.